Refrigerants and methods of transferring heat



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PATENT OFFICE BEFRIGEBANTB AND METHODS OI TBANSFERRING HEAT JosephFleischer, Godfrey Township, Madison County, Ill., asllgnor, by melneassignments, to General Motors Corporation, Dayton, Ohio, a

corporation of Delaware No Drawing. Original application April 35, 1082.

Serial No. 808,574. Divided and Hill application February 4, 1937,Serial No. 124,081

3 Claims.

This application is a division of my copending application, Serial No.608,574, filed April 30, 1932, now matured into Patent No. 2,101,993,is-

- sued Dec. 14, 1937.

This invention relates to chemistry and more particularly torefrigerants and the art of transferring heat fromone point to anotherpoint.

Heretofore refrigerant mixtures have been provided for the allegedpurpose of combining the beneficial properties of each refrigerant whileat the same time eliminating the undesirable properties of eachrefrigerant. These mixtures have not been commercially practicable forthe reason that no refrigerant mixture, as far as I am aware, has beenused that boils at a constant temperature. On the other hand,fractionation has always occurred heretofore in such mixtures resultingin higher head or condenser pressures with lower evaporator pressuresnecessay in the system and hence a material loss in efficiency inoperation.

My invention has for its objects to provide mixtures of two or morerefrigerants forming azeotropic mixtures, which mixtures boil at aconstant temperature as if the mixture were composed of but a singlesubtsance.

When an azeotropic mixture is employed as a refrigerant, nofractionation occurs and therefore there is no loss in efficiencyresulting therefrom on account of the resulting higher head or condenserpressures and necessarily lower evaporator pressures. The advantages ofsuch a mixture are obvious for it is possible by employing such amixture to reduce the undesirable properties of one or both of therefrigerants such as reducing the flammability of the refrigerant oreven entirely eliminating the flammability as well as to reduce thetoxicity of the refrigerant and also the corrosive effect thereof. Suchazeotropic mixtures also make it possible to provide a dif ferentboiling point and different evaporating and condensing pressures whileat the same time retaining the advantageous features of certainrefrigerants such as that of low cost.

One of the mixtures I have found to be advantageous is that of sulphurdioxide and dimethyl ether. Although sulphur dioxide has a boiling pointof l3.5 F. and dimethyl ether has a boiling point of -12.5 FL, I findthatiwhen these liquids, sulphur dioxide and dimethyl ether are mixed inthe proportions of approximately 65 to 35 by weight, an azeotropicmixture is formed having a constant boiling point of 325 F. This DOSES.

therefore provides a mixture with a higher boiling point. This mixturehas the advantage of being exceedingly non-corrosive, stable and muchless flammable than dimethyl ether alone. This militule also has theadvantage of being low in cos Another mixture I have found to beadvantageous is that of dichloro-tetra-fluoro-ethane and butane in theproportions of approximately 59 to 41 by weight. This forms anazeotropic mixture having a boiling point of approximately 28 F. Amongthe advantageous properties of this mixture are that it is a highlyefficient refrigerant for compression refrigerating systems since it hasa very high latent heat and that it retains. most of the valuableproperties of the fluorine refrigerants, yet is materially lower incost.

Another example of such a mixture is that of refrigerants but which hasthe objection of hav ing a boiling point too high for ordinary pur- Thismixture therefore has the advantages of trichloro-monofiuoro-methaneand, in addition, has a lower boiling point and is lower in cost.

Another example is that of trichloro-moncfiuoro-methane and acetaldehydein the propertions of 55 to 45 by weight which forms an azeotropicmixture having a constant boiling point of What is claimed is asfollows:

1. The process of transferring heat which comprises evaporating anazeotropic mixture of a haloiiuoro-derivative of an aliphatichydrocarbon and butane, and condensing the evaporated azeotropicmixture.

2. The process of transferring heat which comprises evaporating anaze'otropic mixture of dichloro-tetrafiuoro-ethane and butane, and thencondensing the evaporated azeotropic mixture.

3. A refrigerant for refrigerating apparatus comprising an azeotropicmixture of dichlorotetrafiuoro-ethane and butane.

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